The present invention relates to a sensor mount for ensuring the proper connection for an electrical sensor.
Automotive safety systems typically employ numerous sensors to detect potential vehicle safety threats and deploy vehicle safety counter measures in reaction to a safety threat or a detected collision event. For example, it is common to use accelerometers to sense vehicle impact and deploy air bags and/or seatbelt pretensioners or other safety-related devices in response thereto. In some vehicle safety systems, the impact sensors, i.e., accelerometers, are located within a centrally located control system. In order to provide reliable acceleration data, impact sensors must be rigidly fixed to the vehicle body part of interest such that reactions upon the vehicle body part can be accurately translated into acceleration data for use by the vehicle safety system.
Accelerometers and impact sensors are typically rigidly affixed to the vehicle by bolts, screws, rivets and the like. Presently, the integrity of the sensor mounting is typically insured by quality control measures with respect to the attachment mechanism. In other words, great care is taken to make sure that the bolt, screw, rivet or solder which attaches the sensor to the vehicle is properly secured or executed. The obvious drawback of monitoring the sensor mount at the time of assembly is that the integrity of the sensor mount can degrade over time. For example, bolts can come loose, clips can break, and solders can crack under certain vehicle operating conditions. Another drawback to monitoring only the attachment process at the time of attachment is that human, machine, or robotic errors could occur in the process itself or in the monitoring process and proper attachment might not occur.
Thus, to ensure the ongoing integrity of the sensor mount, some vehicle manufacturers pass current through the attachment mechanism, i.e., the attaching bolt, to create an electrical circuit which can be monitored to ensure the integrity of the sensor mount. One drawback with such a monitoring scheme, however, is that a loose bolt or rivet can sufficiently maintain the electrical monitoring circuit connection, yet fail to rigidly affix the sensor to the vehicle. This can result in potentially corrupt sensor data in view of a false belief that the sensor is properly attached. This is because the conduction of electrical current is not a direct measurement of the attachment force or integrity. Another drawback is that the electrical current monitoring scheme can be impossible to use if the body part of interest is made of non-conductive material which is becoming more prevalent with the increased use lightweight composite material in automotive designs. In such cases, it would be necessary to add a conductive bracket to the sensor and attach the bracket to a conductive structure of the vehicle. This adds unnecessary weight, cost and complexity. Another drawback with such a sensor mount monitoring scheme is that as additional impact sensors are used at various locations throughout the vehicle, such as in the doors and front and rear fascias, the expense of the monitoring scheme becomes undesirable.
Accordingly, there is a need for an improved sensor-mounting assembly which provides a robust sensor connecting mechanism and ensures the continuous integrity of the sensor mount.
The present invention provides an improved electrical sensor mount which overcomes the drawbacks associated with present sensor mounting schemes. A sensor mount assembly including a housing, fastener and a lever mechanism is provided. The housing contains a sensor having two electrical leads and includes an integral flange adapted to receive a fastener. The fastener includes a body and a head. The fastener body is received in the flange to secure the housing to a mount. The lever mechanism is proximate the flange and includes a contact block and a conductor. The contact block is acted upon by the fastener head to move the lever mechanism and, hence the conductor, between a first position and a second position. The first position corresponds to an unmounted sensor and creates a short circuit condition between the two electrical leads. The second position corresponds to a properly mounted sensor and creates an open circuit between the two electrical leads such that the electrical circuit path of the overall system includes the sensor within the housing.
In one embodiment, the lever mechanism includes a lever ring positioned about the fastener body between the fastener head and an upper surface of the flange. The lever ring includes a conductive bar passing within the housing. The lever ring is acted upon by the fastener head and the upper surface to be moveable between a first position wherein the conductive bar is in electrical contact with the two electrical leads to create a short circuit, and a second position wherein the conductive bar creates an open circuit with respect to the two electrical leads.
In another embodiment, the lever mechanism includes a split flange design wherein each portion of the flange includes an electrical contact associated with a respective electrical lead within the housing. Securing the fastener within the mount forces the two flange portions and, hence, the electrical contacts therein, together to create a short circuit between the two electrical leads.